JP2017211315A - Device for detecting object to be conveyed, device that discharges liquid, method for detecting object to be conveyed, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the position of an object to be conveyed in a conveyance direction or an orthogonal direction.SOLUTION: A device for detecting an object to be conveyed includes an optical sensor that receives light reflected on an object to be conveyed, sets the optical zoom magnification related to the optical sensor on the basis of the speed at which the object to be conveyed is conveyed, and outputs, by using the optical sensor, a detection result indicating the position or the speed of the object to be conveyed in at least either one of a conveyance direction in which the object to be conveyed is conveyed or a direction orthogonal to the conveyance direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transported object detection device, a device for ejecting liquid, a transported object detection method, and a program.

  2. Description of the Related Art Conventionally, a method for forming an image by a so-called ink jet method for discharging ink from a print head is known. A method for improving the print quality of an image printed on a print medium by this image formation is known.

  For example, a method of adjusting the position of the print head is known in order to improve print quality. Specifically, first, a position change in the lateral direction of a web that is a printing medium passing through a continuous paper printing system is detected by a sensor. A method of adjusting the position of the print head in the lateral direction so as to compensate for the position variation detected by this sensor is known (see, for example, Patent Document 1).

  However, in order to further improve the image quality of an image to be formed, the direction in which the object is transported (hereinafter referred to as “transport direction”) or the direction orthogonal to the transport direction (hereinafter simply referred to as “orthogonal direction”). In other words, in order to improve the landing position of the liquid to be discharged, the position of the object to be transported may be required to be detected with high accuracy. On the other hand, in the conventional technology, there is a problem that the position or the like of the object to be transported may not be accurately detected in the transport direction or the orthogonal direction.

  An object of one aspect of the present invention is to provide a transported object detection apparatus that accurately detects the position of a transported object in the transport direction or the orthogonal direction.

In order to solve the above-described problem, a transported object detection device according to one aspect of the present invention is provided.
An optical sensor for receiving the light reflected by the conveyed object;
A setting unit for setting an optical zoom magnification according to the optical sensor based on a speed at which the object is conveyed;
A detection unit that outputs a detection result indicating a position or speed of the object to be conveyed in at least one of a conveyance direction in which the object to be conveyed is conveyed or a direction orthogonal to the conveyance direction using the optical sensor;
It is characterized by providing.

  In the transport direction or the orthogonal direction, the position of the transported object can be detected with high accuracy.

It is the schematic which shows an example of the apparatus which discharges the liquid which concerns on one Embodiment of this invention. It is the schematic which shows the example of whole structure of the apparatus which discharges the liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the external shape of the liquid discharge head unit which concerns on one Embodiment of this invention. It is the schematic which shows an example of the hardware constitutions of the detection part which concerns on one Embodiment of this invention. It is the schematic which shows an example of the 2nd hardware constitutions of the detection apparatus used for the detection part which concerns on one Embodiment of this invention. It is the schematic which shows an example of the 3rd hardware constitutions of the detection apparatus used for the detection part which concerns on one Embodiment of this invention. It is the schematic which shows an example of the some imaging lens used for the detection part which concerns on one Embodiment of this invention. It is a functional block diagram which shows an example of a function structure of the detection part which concerns on one Embodiment of this invention. It is an external view which shows an example of the apparatus which implement | achieves the detection part which concerns on one Embodiment of this invention. FIG. 6 is a diagram illustrating an example in which the position of a recording medium varies in an orthogonal direction. It is a figure which shows an example of the cause which color misregistration arises. It is a block diagram which shows an example of the hardware constitutions of the control part which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the hardware constitutions of the data management apparatus which the control part which concerns on one Embodiment of this invention has. It is a block diagram which shows an example of the hardware constitutions of the image output apparatus which the control part which concerns on one Embodiment of this invention has. It is a flowchart which shows an example of the whole process by the apparatus which discharges the liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the optical zoom magnification which the apparatus which discharges the liquid which concerns on one Embodiment of this invention sets. It is a figure which shows an example of the test pattern which the apparatus which discharges the liquid which concerns on one Embodiment of this invention uses. It is a figure which shows the example of a process result of the whole process by the apparatus which discharges the liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the position where the sensor in the apparatus which discharges the liquid which concerns on one Embodiment of this invention is installed. It is a figure which shows an example of the hardware constitutions in a 1st comparative example. It is a figure which shows the example of a process result of the whole process by the apparatus which discharges the liquid which concerns on a 1st comparative example. It is a figure which shows the example of a process result of the whole process by the apparatus which discharges the liquid which concerns on a 2nd comparative example. It is a figure which shows an example of the position in which the sensor in the apparatus which discharges the liquid which concerns on a comparative example is installed. It is a functional block diagram which shows an example of a function structure of the apparatus which discharges the liquid which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that, in the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<Example of overall configuration>
FIG. 1 is a schematic view showing an example of an apparatus for ejecting liquid according to an embodiment of the present invention. For example, an apparatus for ejecting liquid is an image forming apparatus as illustrated. In such an image forming apparatus, the discharged liquid is a recording liquid such as aqueous or oil-based ink. Hereinafter, an example in which the apparatus for ejecting liquid is the image forming apparatus 110 will be described.

  The conveyed object is, for example, a recording medium. In the illustrated example, the image forming apparatus 110 forms an image by ejecting liquid onto a web 120 that is an example of a recording medium conveyed by a roller 130 or the like. The web 120 is a so-called continuous paper printing medium or the like. That is, the web 120 is roll-shaped paper or the like that can be wound. As described above, the image forming apparatus 110 is a so-called production printer. In the following description, an example will be described in which the roller 130 adjusts the tension of the web 120 and the web 120 is conveyed in the illustrated direction (hereinafter referred to as “conveying direction 10”). Further, in the figure, the direction orthogonal to the transport direction 10 is an example of the orthogonal direction 20. Further, in this example, the image forming apparatus 110 ejects ink of each of the four colors of black (K), cyan (C), magenta (M), and yellow (Y) to form an image on a predetermined portion of the web 120. Is an ink jet printer.

  FIG. 2 is a schematic diagram illustrating an example of the overall configuration of a device for ejecting liquid according to an embodiment of the present invention. As shown in the figure, the image forming apparatus 110 includes four liquid discharge head units for discharging each of the four ink colors.

  Each liquid discharge head unit discharges each liquid of each color to the web 120 conveyed in the conveyance direction 10. The web 120 is conveyed by two nip rollers, a roller 230, and the like. Hereinafter, of these two nip rollers, the nip roller installed on the upstream side of each liquid discharge head unit is referred to as “first nip roller NR1”. On the other hand, a nip roller installed on the downstream side of the first nip roller NR1 and each liquid discharge head unit is referred to as a “second nip roller NR2”. Each nip roller rotates with a conveyed object such as the web 120 interposed therebetween, as shown in the figure. Thus, each nip roller and roller 230 are an actuator or a mechanism that conveys the web 120 or the like in a predetermined direction.

  The recording medium of the web 120 is preferably long. Specifically, the length of the recording medium is preferably longer than the distance between the first nip roller NR1 and the second nip roller NR2. Furthermore, the recording medium is not limited to the web. In other words, the recording medium may be paper that is folded and stored, so-called “Z paper” or the like.

  Hereinafter, in the illustrated overall configuration example, each liquid discharge head unit is installed in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side toward the downstream side. To do. That is, the liquid discharge head unit installed on the most upstream side (hereinafter referred to as “black liquid discharge head unit 210K”) is used for black (K). A liquid discharge head unit (hereinafter referred to as “cyan liquid discharge head unit 210C”) installed next to the black liquid discharge head unit 210K is used for cyan (C). Further, a liquid discharge head unit (hereinafter referred to as “magenta liquid discharge head 210M”) installed next to the cyan liquid discharge head unit 210C is used for magenta (M). Subsequently, the liquid discharge head unit (hereinafter referred to as “yellow liquid discharge head unit 210Y”) installed on the most downstream side is used for yellow (Y).

  Each liquid discharge head unit discharges each color ink to a predetermined portion of the web 120 based on image data or the like. The position at which this ink is ejected (hereinafter referred to as “ejection position”) is substantially equal to the position at which the liquid ejected from the liquid ejection head lands on the recording medium, that is, directly under the liquid ejection head. In this example, black ink is ejected to the ejection position of the black liquid ejection head unit 210K (hereinafter referred to as “black ejection position PK”). Similarly, cyan ink is ejected to the ejection position of the cyan liquid ejection head unit 210C (hereinafter referred to as “cyan ejection position PC”). Further, the magenta ink is ejected to the ejection position of the magenta liquid ejection head unit 210M (hereinafter referred to as “magenta ejection position PM”). The yellow ink is ejected to the ejection position of the yellow liquid ejection head unit 210Y (hereinafter referred to as “yellow ejection position PY”). Each timing at which each liquid ejection head unit ejects ink is controlled by a controller 520 connected to each liquid ejection head unit.

  A plurality of rollers are installed for each liquid discharge head unit. As shown in the figure, for example, the plurality of rollers are respectively installed on the upstream side and the downstream side across the liquid discharge head units. In the illustrated example, for each liquid discharge head unit, a roller (hereinafter referred to as a “first roller”) used to transport the web 120 to each discharge position is installed on the upstream side of each liquid discharge head unit. The Further, rollers (hereinafter referred to as “second rollers”) used to convey the web 120 downstream from the respective ejection positions are respectively installed on the downstream side of the respective liquid ejection head units. In this way, when the first roller and the second roller are installed, so-called “flapping” can be reduced at each discharge position. The first roller and the second roller are used to transport the recording medium, and are, for example, driven rollers. Further, the first roller and the second roller may be driving rollers.

  Specifically, a black first roller CR1K used for transporting the web 120 to the black ejection position PK is installed at a predetermined portion of the web 120 in order to eject black ink. On the other hand, a second black roller CR2K used for conveying the web 120 from the black discharge position PK to the downstream side is installed. Similarly, a cyan first roller CR1C and a cyan second roller CR2C are respectively installed on the cyan liquid discharge head unit 210C. Further, a first magenta roller CR1M and a second magenta roller CR2M are installed for the magenta liquid ejection head unit 210M. Further, a yellow first roller CR1Y and a yellow second roller CR2Y are respectively installed on the yellow liquid discharge head unit 210Y.

  An example of the outer shape of the liquid discharge head unit will be described with reference to FIG. Here, FIG. 3A is a schematic plan view showing an example of four liquid discharge head units 210K to 210Y of the image forming apparatus 110 according to the embodiment of the present invention.

  As shown in FIG. 3A, the liquid ejection head unit is a full-line head unit in this embodiment. That is, the image forming apparatus 110 includes four liquid discharge head units 210K, 210C corresponding to black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the conveyance direction 10 of the recording medium. 210M and 210Y are arranged.

  Here, the black (K) liquid discharge head unit 210K has four heads 210K-1, 210K-2, 210K-3, and 210K-4 in a direction orthogonal to the conveyance direction 10 of the web 120 in this embodiment. Arranged in a staggered pattern. As a result, the image forming apparatus 110 can form an image over the entire width direction (direction perpendicular to the transport direction) of the image forming area (printing area) of the web 120. The configurations of the other liquid discharge head units 210C, 210M, and 210Y are the same as the configuration of the black (K) liquid discharge head unit 210K, and thus the description thereof is omitted.

  Although an example in which the liquid discharge head unit is configured with four heads has been described here, the liquid discharge head unit may be configured with a single head.

<Example of detection unit>
For each liquid ejection head unit, a sensor that detects the position of the recording medium in the transport direction or the orthogonal direction, which is an example of a detection unit, is installed. As this sensor, an optical sensor using light such as laser, air pressure, photoelectric, ultrasonic wave or infrared ray is used. The optical sensor may be a CCD (Charge Coupled Device) camera, for example. That is, the sensor constituting the detection unit is, for example, a sensor that can detect the edge of the recording medium. Moreover, the structure demonstrated below may be sufficient as a sensor, for example.

  As shown in FIG. 2, a setting device 521 is connected to the sensor. The setting device 521 sets an aperture value, an exposure time, and the like related to the sensor based on a result calculated by each sensor or the controller 520 or the like. Details of the setting will be described later.

  FIG. 4 is a schematic diagram illustrating an example of a hardware configuration of a detection unit according to an embodiment of the present invention. For example, the sensor is realized by a detection device 50, a first light source 51A, a second light source 51B, a control device 52, a storage device 53, an arithmetic device 54, and the like as illustrated.

  The web 120 which is an example of the detection target is irradiated with laser light or the like from the first light source 51A and the second light source 51B. The position where the first light source 51A emits light is referred to as “A position”, and similarly, the position where the second light source 51B applies light is referred to as “B position”.

  The first light source 51A and the second light source 51B include a light emitting element that emits laser light and a collimator lens that makes the laser light emitted from the light emitting element substantially parallel. The first light source 51 </ b> A and the second light source 51 </ b> B are installed at a position where laser light is irradiated from an oblique direction with respect to the surface of the web 120.

  The detection device 50 includes the area sensor 11, a first imaging lens 12A at a position facing the “A position”, and a second imaging lens 12B at a position facing the “B position”.

  The area sensor 11 is, for example, a sensor configured to form the image sensor 112 on the silicon substrate 111. It is assumed that there are an “A region 11A” and a “B region 11B” on the imaging device 112, each of which can acquire a two-dimensional image. The area sensor 11 is, for example, a CCD sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, a photodiode array, or the like. The area sensor 11 is accommodated in the housing 13. Further, the first imaging lens 12A and the second imaging lens 12B are held by the first lens barrel 13A and the second lens barrel 13B, respectively.

  In this example, as illustrated, the optical axis of the first imaging lens 12A coincides with the center of the “A region 11A”. Similarly, the optical axis of the second imaging lens 12B coincides with the center of the “B region 11B”. Then, the first imaging lens 12A and the second imaging lens 12B form a two-dimensional image by forming images of light on the “A region 11A” and the “B region 11B”, respectively.

  The first imaging lens 12A and the second imaging lens 12B are so-called zoom lenses ZM, which can change the optical zoom magnification when the position or the like is changed.

  The detection device 50 is not limited to the configuration illustrated in FIG. For example, the detection device 50 may have a configuration described below.

  FIG. 5 is a schematic diagram illustrating an example of a second hardware configuration of a detection device used in the detection unit according to the embodiment of the present invention. Compared with the configuration shown in FIG. 4, the configuration of the detection apparatus 50 shown in FIG. 5 is different in that the first imaging lens 12A and the second imaging lens 12B are integrated to form the lens 12C. On the other hand, the area sensor 11 and the like have the same configuration as shown in FIG.

  In this example, it is desirable to use the aperture 121 and the like so that the images of the first imaging lens 12A and the second imaging lens 12B do not interfere and form an image. As described above, when the aperture 121 or the like is used, regions where the images of the first imaging lens 12A and the second imaging lens 12B are formed can be limited. Therefore, interference between the respective image formations can be reduced, and the detection apparatus 50 can generate images at the respective positions at the “A position” and the “B position” shown in FIG.

  FIG. 6 is a schematic diagram illustrating an example of a third hardware configuration of the detection device used in the detection unit according to the embodiment of the present invention. Compared with the configuration shown in FIG. 5, the configuration of the detection apparatus 50 shown in FIG. 6A is different in that the area sensor 11 is the second area sensor 11 ′. On the other hand, the configuration of the first imaging lens 12A, the second imaging lens 12B, and the like is the same as that shown in FIG. 5, for example.

  The second area sensor 11 ′ has, for example, the configuration shown in FIG. Specifically, as illustrated in FIG. 6B, a plurality of imaging elements b are formed on the wafer a. Next, image sensors as illustrated in FIG. 6B are cut out from the wafer a. The first image sensor 112 </ b> A and the second image sensor 112 </ b> B, which are a plurality of image sensors to be cut out, are formed on the silicon substrate 111. In contrast, the positions of the first imaging lens 12A and the second imaging lens 12B are determined in accordance with the interval between the first imaging element 112A and the second imaging element 112B.

  An image sensor is often manufactured for imaging. For this reason, the ratio between the X direction and the Y direction of the image sensor, that is, the aspect ratio, is often a ratio that matches the image format, such as square, “4: 3”, or “16: 9”. In the present embodiment, images at two or more points that are separated by a certain interval are captured. Specifically, an image is captured for each point that is spaced apart in the X direction, which is one direction in two dimensions, that is, in the transport direction 10 (FIG. 4). On the other hand, the image sensor has an aspect ratio that matches the image format. Therefore, in the case of imaging at two points that are separated by a certain interval in the X direction, the imaging element in the Y direction may not be used. Further, when the pixel density is increased, an image sensor having a high pixel density is used in either the X direction or the Y direction, which may increase the cost.

  Therefore, with the configuration illustrated in FIG. 6, the first image sensor 112 </ b> A and the second image sensor 112 </ b> B that are spaced apart from each other can be formed on the silicon substrate 111. Therefore, the number of image sensors that do not use the image sensor in the Y direction can be reduced. Therefore, waste of the image sensor can be reduced. Further, since the first image sensor 112A and the second image sensor 112B are formed by a highly accurate semiconductor process, the interval between the first image sensor 112A and the second image sensor 112B can be accurately performed.

  FIG. 7 is a schematic diagram illustrating an example of a plurality of imaging lenses used in a detection unit according to an embodiment of the present invention. A lens array as shown may be used to implement the detector.

  The illustrated lens array has a configuration in which two or more lenses are integrated. Specifically, the illustrated lens array includes a total of nine imaging lenses A1 to C3 in three rows and three columns, for example, in the vertical and horizontal directions. When such a lens array is used, an image showing nine points can be taken. In this case, an area sensor having nine imaging areas is used.

  In this way, for example, calculations for two imaging regions are easily executed simultaneously, that is, executed in parallel. Next, when each calculation result is averaged or error elimination is performed, the detection apparatus can calculate with high accuracy or improve the stability of calculation compared to the case where one calculation result is used. can do. In some cases, the calculation is executed based on application software whose speed varies. Even in this case, since the area where the correlation calculation can be performed is widened, it is easy to obtain a speed calculation result with high accuracy.

  Returning to FIG. 4, the control device 52 controls the detection device 50 and the like. Specifically, the control device 52 controls the shutter timing of the area sensor 11 by outputting a signal to the detection device 50 or the like. In addition, the control device 52 performs control so that a two-dimensional image can be acquired from the detection device 50. Next, the control device 52 sends the acquired two-dimensional image to the storage device 53.

  The storage device 53 is a so-called memory or the like. It is desirable that the two-dimensional image sent from the control device 52 be divided and stored in different storage areas.

  The arithmetic device 54 is a microcomputer or the like. That is, the computing device 54 performs computations for realizing various processes using image data stored in the storage device 53.

  The control device 52 and the arithmetic device 54 are, for example, a CPU (Central Processing Unit) or an electronic circuit. Note that the control device 52, the storage device 53, and the arithmetic device 54 may not be different devices. For example, the control device 52 and the calculation device 54 may be one CPU or the like.

  Hereinafter, an example in which there are two optical systems shown in FIG. 4 will be described. In the embodiment according to the present invention, the number of optical systems may be three or more.

  Also, as shown in FIG. 4, zoom mechanisms such as actuators ACA and ACB are installed in the first imaging lens 12A and the second imaging lens 12B, respectively. For example, when the optical zoom magnification is changed, the zoom mechanism changes the position of each of the first imaging lens 12A and the second imaging lens 12B based on the set optical zoom magnification, and becomes the optical zoom magnification. To be controlled.

  Each optical system may have a stop. For example, the diaphragm is an electric iris diaphragm or the like. The diaphragm is controlled by an actuator or the like. When the aperture is controlled, the amount of received light is adjusted.

  In addition, it is desirable to control the shutter speed and adjust the exposure time. Further, the control is performed by, for example, the control device 52, and the shutter speed, the aperture value, and the like are set by the setting device 521 and the like. Details of the control method and the like will be described later.

  FIG. 8 is a functional block diagram illustrating an example of a functional configuration of the detection unit according to an embodiment of the present invention. Hereinafter, as illustrated, a combination of a black liquid discharge head unit 210K and a cyan liquid discharge head unit 210C among detection units installed for each head unit will be described as an example. Further, as shown in the figure, the detection unit 52A for the black liquid ejection head unit 210K outputs the detection result related to the “A position”, and the detection unit 52B for the cyan liquid ejection head unit 210C detects the detection related to the “B position”. An example of outputting the result will be described. First, the detection unit 52A for the black liquid ejection head unit 210K includes, for example, an imaging unit 16A, an imaging control unit 14A, an image storage unit 15A, and the like. In this example, the detection unit 52B for the cyan liquid ejection head unit 210C has, for example, the same configuration as the detection unit 52A, and includes an imaging unit 16B, an imaging control unit 14B, an image storage unit 15B, and the like. Hereinafter, the detection unit 52A will be described as an example.

  The imaging unit 16A images the web 120 conveyed in the conveyance direction 10 as illustrated. Note that the imaging unit 16A is realized by, for example, the detection device 50 or the like (FIG. 4 or the like).

  The imaging control unit 14A includes a zoom control unit 141A and an image capturing unit 142A. Note that the imaging control unit 14A is realized by, for example, the control device 52 or the like (FIG. 4).

  The image capturing unit 142A acquires an image captured by the imaging unit 16A.

  The zoom control unit 141A controls the optical zoom magnification that the imaging unit 16A images.

  The image storage unit 15A stores the image captured by the imaging control unit 14A. The image storage unit 15A is realized by, for example, the storage device 53 or the like (FIG. 4).

  Further, the imaging control unit 14A may include a shutter control unit that controls the shutter speed. Hereinafter, an example in which the imaging control unit 14A controls the shutter speed will be described.

  The calculation unit 53F can calculate the position of the pattern that the web 120 has, the conveyance speed at which the web 120 is conveyed, and the conveyance amount at which the web 120 is conveyed based on the images stored in the image storage units 15A and 15B. .

  Next, the calculation unit 53F calculates an exposure time, an optical zoom magnification, and the like based on the conveyance speed. For example, when the conveyance speed is high, the calculation unit 53F calculates so that the optical zoom magnification is low, that is, the captured image is enlarged. If the conveyance speed is high, the calculation unit 53F calculates the exposure time to be short by increasing the shutter speed.

  On the other hand, when the conveyance speed is low, the calculation unit 53F calculates so that the optical zoom magnification is high, that is, the captured image is reduced. Further, when the conveyance speed is low, the calculation unit 53F calculates the exposure time by decreasing the shutter speed.

  As described above, the calculation unit 53F sets the optical zoom magnification and the like based on the conveyance speed. Details of the settings relating to the optical zoom magnification and the like will be described later.

  Further, the calculation unit 53F outputs data of the time difference Δt indicating the shutter timing to the shutter control unit or the like. That is, the calculation unit 53F indicates the shutter timing to the shutter control unit or the like so that the image indicating the “A position” and the image indicating the “B position” are captured with a time difference Δt. The calculation unit 53F may control a motor or the like that conveys the web 120 so that the calculated conveyance speed is obtained. Note that the calculation unit 53F is realized by, for example, the controller 520 or the like (FIG. 2).

  The web 120 is a member having scattering properties on the surface or inside thereof. Therefore, when the web 120 is irradiated with laser light, the reflected light is diffusely reflected. A pattern is formed on the web 120 by the diffuse reflection. That is, the pattern is a so-called speckle pattern called “speckle”. Therefore, when the web 120 is imaged, an image showing a speckle pattern is obtained. Since the position where the speckle pattern is present is known from this image, it is possible to detect where the predetermined position of the web 120 is. This speckle pattern is generated because the irradiated laser beam interferes with the uneven shape formed on the surface or inside of the web 120.

  Therefore, when the web 120 is conveyed, the speckle pattern of the web 120 is also conveyed. Therefore, when the same speckle pattern is detected at different times, the transport amount is obtained. That is, when the same speckle pattern is detected and the conveyance amount of the pattern is obtained, the calculation unit 53F can obtain the conveyance amount of the web 120. When the transport amount obtained is converted per unit time, the calculation unit 53F can determine the transport speed at which the web 120 is transported.

  Specifically, assuming that the conveyance speed V [mm / s] and the relative distance L [mm] that is the interval at which the first imaging lens 12A and the second imaging lens 12B are installed in the conveyance direction 10, the following equation (1) It can be shown as

Δt = L / V (1)
In the above equation (1), the relative distance L [mm] is an interval between the first imaging lens 12A and the second imaging lens 12B, and can be obtained in advance. Therefore, when the time difference Δt is determined, the calculation unit 53F can obtain the transport speed V [mm / s] based on the above equation (1). As described above, based on the speckle pattern, the image forming apparatus can accurately obtain the position in the transport direction, the transport amount and the transport speed, or a combination thereof. Note that the image forming apparatus may output a combination of any of the position in the transport direction, the transport amount, and the transport speed.

  As shown in FIG. 4, the first imaging lens 12 </ b> A and the second imaging lens 12 </ b> B are installed at regular intervals in the transport direction 10. Then, the web 120 is imaged at each position via the first imaging lens 12A and the second imaging lens 12B. Thus, based on the speckle pattern, the image forming apparatus can obtain a detection result indicating the position of the web 120 with high accuracy in the transport direction or the orthogonal direction.

  Further, the detection result may indicate a relative position. Specifically, the relative position indicates a difference between a position detected by one of the sensors and a position detected by a different sensor. In addition, the relative position may be a difference between positions in a plurality of images obtained by any one of the sensors. That is, for example, the relative position may be a difference between the position detected in the previous frame and the position detected in the next frame. Thus, the relative position indicates the amount of deviation from the position detected by the previous frame or other sensor.

  The sensor may detect the position in the transport direction. That is, the sensor may be used to detect the respective positions in the transport direction and the direction orthogonal to the transport direction. When used in this manner, the cost can be reduced in each direction. In addition, since the number of sensors can be reduced, space can be saved.

  Further, the calculation unit 53F performs a cross-correlation operation on the image data D1 (n) and D2 (n) indicating the images captured by the detection units 52A and 52B. Hereinafter, an image generated by the cross correlation calculation is referred to as a “correlation image”. For example, the calculation unit 53F calculates the shift amount ΔD (n) based on the correlation image.

  For example, the cross-correlation calculation is a calculation represented by the following equation (2).

D1 * D2 * = F-1 [F [D1] · F [D2] *] (2)
In the above equation (2), the image data D1 (n), that is, the image data indicating the image picked up at the “position A” is “D1”. Similarly, in the above equation (2), image data D2 (n), that is, image data indicating an image captured at the “B position” is “D2”. Furthermore, in the above equation (2), the Fourier transform is indicated by “F []”, and the inverse Fourier transform is indicated by “F-1 []”. Furthermore, in the above equation (2), the complex conjugate is indicated by “*” and the cross-correlation operation is indicated by “★”.

  As shown in the above equation (2), when the cross-correlation calculation “D1 * D2” is performed on the image data D1 and D2, image data indicating a correlation image is obtained. If the image data D1 and D2 are two-dimensional image data, the image data indicating the correlation image is two-dimensional image data. When the image data D1 and D2 are one-dimensional image data, the image data indicating the correlation image is one-dimensional image data.

  In the correlation image, for example, when a broad luminance distribution becomes a problem, the phase only correlation method may be used. The phase only correlation method is, for example, a calculation represented by the following equation (3).

D1 * D2 * = F-1 [P [F [D1]] · P [F [D2] *]] (3)
In the above equation (3), “P []” indicates that only the phase is extracted from the complex amplitude. The amplitudes are all “1”.

  In this way, the calculation unit 53F can calculate the shift amount ΔD (n) based on the correlation image even with a broad luminance distribution.

  The correlation image indicates the correlation between the image data D1 and D2. Specifically, as the degree of coincidence between the image data D1 and D2 increases, a sharp peak, that is, a so-called correlation peak luminance is output at a position closer to the center of the correlation image. When the image data D1 and D2 match, the center and peak position of the correlation image overlap.

  Based on the timing calculated by such calculation, the black liquid discharge head unit 210K and the cyan liquid discharge head unit 210C each discharge liquid. The liquid discharge timing is controlled by the first signal SIG1 for the black liquid discharge head unit 210K output from the controller 520, the second signal SIG2 for the cyan liquid discharge head unit 210C, and the like. As shown in the drawing, based on the result of calculation by the calculation unit 53F, the control unit 54F outputs a signal to control the timing. Note that the control unit 54F is realized by, for example, the controller 520 or the like.

  Further, the calculation unit 53F outputs the conveyance speed V calculated based on the detection result to the setting unit 55F. Then, the setting unit 55F calculates the optical zoom magnification, the aperture value, the exposure time, and the like based on the conveyance speed V received from the outside such as the calculation unit 53F. Further, the conveyance speed V may be input to the setting unit 55F based on the operation mode such as the resolution of the output image of the image forming apparatus. The setting unit 55F is realized by, for example, a setting device (FIG. 4) such as a microcomputer.

  The setting unit 55F decreases the optical zoom magnification when the transport speed V is high. On the other hand, the setting unit 55F increases the optical zoom magnification when the transport speed V is low. Specifically, the zoom control units 141A and 141B control the zoom lens ZM so that the optical zoom magnification set by the setting unit 55F is obtained. The zoom controllers 141A and 141B are realized by the control device 52, actuators ACA and ACB, and the like.

  When an aperture value or the like is set, the aperture control unit or the like controls the aperture so that the aperture value set by the setting unit 55F is obtained. The aperture control unit is realized by, for example, the control device 52 (FIG. 4) and an actuator.

  Similarly, the shutter control unit controls the shutter speed and the like so that the exposure time or the shutter speed set by the setting unit 55F is obtained.

  In this way, the detection unit can capture an image based on the exposure time and the aperture value corresponding to the transport speed V. The calculation and setting may be performed by the controller 520 or the like.

  Specifically, the aperture value is calculated such that the received light amount is inversely proportional to the exposure time determined by the conveyance speed V. For example, the aperture value is calculated by the following equation (4).

I = Io × (NA × Mo) ²
Depth of focus = ± k × wavelength / {2 × (numerical aperture) ² } (4)
In the above formula (4), “I” indicates the brightness of the image. “Io” indicates the brightness of the sample surface. Further, in the above equation (4), “NA” indicates a numerical aperture that is an example of an aperture value. In the above formula (4), “Mo” indicates the magnification of the objective lens. In other words, the numerical aperture is set for the stop. In the case expressed by the above equation (4), the amount of received light is proportional to the square of the numerical aperture. Therefore, when the exposure time is "1/2" times, the numerical aperture is "√2" times. The

  Note that the image forming apparatus may store the optical zoom magnification, the exposure time, and the aperture value corresponding to the conveyance speed in a lookup table or the like through experiments or evaluations performed in advance. Then, the setting unit 55F specifies the optical zoom magnification, the exposure time, and the aperture value according to the conveyance speed from a lookup table or the like, and sets the optical zoom magnification, the exposure time, the aperture value, and the like.

  The optical zoom magnification is calculated as follows, for example.

  First, the shutter speed is set corresponding to the transport speed V. Specifically, when the transport speed V is high, the object to be transported moves at a high speed, so the shutter speed is often set to be high. That is, the shutter speed is set to be proportional to the conveyance speed V.

  When the shutter speed is set to be high, the amount of received light decreases. That is, since the shutter speed is set in accordance with the conveyance speed V, the amount of received light is in inverse proportion to the conveyance speed V. Therefore, when the transport speed V is high, the optical zoom magnification is set to decrease. Also, if the optical zoom magnification is lowered, the amount of blurring for one pixel can be reduced.

  Specifically, the optical zoom magnification is calculated as follows. Hereinafter, as a specific example, an example will be described in which the conveyance speed V is changed from “1 m / s” to “3 m / s”, that is, the conveyance speed is tripled. Further, it is assumed that the area to be imaged is a uniform illumination condition and a lens having the same aperture.

  First, the shutter speed is set to be tripled as the conveyance speed V is tripled. Therefore, the amount of received light becomes 1/3 times and becomes darker by changing the shutter speed. On the other hand, if the openings are the same, the amount of light received is determined by the light receiving area. In addition, the amount of received light is inversely proportional to the square of the optical zoom magnification. Therefore, in order to triple the amount of received light, the following equation (5) is calculated.

Shutter speed 3 times ... Received light amount 1/3
Received light quantity 3 times = 1 / (1 / √3) ² = 3 times ... Optical zoom magnification 1 / √3 ≒ 0.57 times (5)
Thus, if the optical zoom magnification is set to be lowered in accordance with the transport speed V, the amount of received light can be maintained or increased. Further, when the optical zoom magnification is lowered, the relative blur amount can be reduced.

  FIG. 9 is an external view showing an example of a device that realizes a detection unit according to an embodiment of the present invention. Further, the detection unit may be realized with a configuration as illustrated.

  The illustrated sensor has a configuration in which a speckle pattern is formed by illuminating an object such as a web. Specifically, the sensor has a semiconductor laser light source (LD) and a collimating optical system (CL). The sensor includes a CMOS image sensor for capturing an image of a speckle pattern, and a telecentric imaging optical system (OL) for condensing and focusing the speckle pattern on the CMOS image sensor.

  In the example of the configuration shown in the figure, the CMOS image sensor acquires a speckle pattern image at each of the time T1 and the time T2 that are separated. Further, the cross-correlation calculation is performed in the FPGA circuit using the speckle pattern image acquired at time T1 and the speckle pattern image acquired at time T2. Based on the movement of the correlation peak position, the CMOS image sensor outputs the amount of movement of the object from time T1 to time T2 in the imaging range. In the example shown in the figure, the size of the sensor is W × D × H = 15 × 60 × 32 [mm].

  The CMOS image sensor is an example of an imaging unit, and the FPGA circuit is an example of an arithmetic device.

  Returning to FIG. 2, in the following description, a sensor installed for the black liquid discharge head unit 210K is referred to as a “black sensor SENK”. Similarly, a sensor installed for the cyan liquid ejection head unit 210C is referred to as “cyan sensor SENC”. Further, a sensor installed for the magenta liquid ejection head unit 210M is referred to as “magenta sensor SENM”. Furthermore, a sensor installed for the yellow liquid discharge head unit 210Y is referred to as “yellow sensor SENY”. In the following description, the black sensor SENK, the cyan sensor SENC, the magenta sensor SENM, and the yellow sensor SENY may be simply referred to as “sensor”.

  In the following description, “position where the sensor is installed” refers to a position where detection or the like is performed. Therefore, it is not necessary to install all devices used for detection or the like at the “position where the sensor is installed”, and devices other than the sensor may be installed at other positions that are connected by a cable or the like. Note that the black sensor SENK, cyan sensor SENC, magenta sensor SENM, and yellow sensor SENY shown in FIG. 2 are examples of positions where the sensors are installed.

  Thus, the position where the sensor is installed is desirably a position close to each discharge position. If a sensor is installed at a position close to each discharge position, the distance between each discharge position and the sensor is shortened. When the distance between each ejection position and the sensor is shortened, errors in detection can be reduced. Therefore, the image forming apparatus can accurately detect the position of the recording medium in the transport direction or the orthogonal direction by the sensor.

  Specifically, the position close to each discharge position is between each first roller and each second roller. In other words, in the illustrated example, the position where the black sensor SENK is installed is desirably the inter-black roller INTK1 as illustrated. Similarly, the position where the cyan sensor SENC is installed is preferably between the cyan rollers INTC1, as shown. Further, the position where the magenta sensor SENM is installed is preferably the magenta roller INTM1 as shown. Furthermore, it is desirable that the position where the yellow sensor SENY is installed is the inter-yellow roller INTY 1 as illustrated. Thus, when a sensor is installed between each roller, the sensor can detect the position of the recording medium at a position close to each ejection position. In many cases, the conveyance speed is relatively stable between the rollers. Therefore, the image forming apparatus can accurately detect the position of the recording medium in the transport direction or the orthogonal direction.

  More preferably, the position where the sensor is installed is more preferably closer to the first roller than the discharge position between the rollers. That is, the position where the sensor is installed is more desirably upstream of each discharge position.

  Specifically, the position where the black sensor SENK is installed is between the black discharge position PK and the position where the first black roller CR1K is installed toward the upstream side (hereinafter referred to as “black upstream section INTK2”). Is more desirable. Similarly, the position where the cyan sensor SENC is installed is from the cyan discharge position PC to the position where the first cyan roller CR1C is installed upstream (hereinafter referred to as “cyan upstream section INTC2”). Is more desirable. Further, the position where the magenta sensor SENM is installed is from the magenta discharge position PM to the position where the first magenta roller CR1M is installed upstream (hereinafter referred to as “magenta upstream section INTM2”). More desirable. Furthermore, the position where the yellow sensor SENY is installed is from the yellow discharge position PY to the position where the first yellow roller CR1Y is installed upstream (hereinafter referred to as “yellow upstream section INTY2”). Is more desirable.

  When sensors are installed in the black upstream section INTK2, the cyan upstream section INTC2, the magenta upstream section INTM2, and the yellow upstream section INTY2, the image forming apparatus accurately positions the recording medium in the transport direction or the orthogonal direction. It can be detected. Furthermore, when a sensor is installed at such a position, the sensor is installed upstream from each discharge position. Therefore, the image forming apparatus can first detect the position of the recording medium with high accuracy in the transport direction or the orthogonal direction by the sensor on the upstream side, and calculate the ejection timing of each liquid ejection head unit. That is, when the web 12 is conveyed to the downstream side while this calculation is performed, each liquid discharge head unit can discharge ink at the calculated timing.

  If the position immediately below each liquid discharge head unit is the position where the sensor is installed, color misregistration may occur due to a delay for the control operation. Therefore, when the position where the sensor is installed is upstream of each ejection position, the image forming apparatus can reduce color misregistration and improve image quality. In addition, it may be restricted that the vicinity of each discharge position and the like is a position where a sensor or the like is installed. Therefore, the position where the sensor is installed is more preferably a position closer to each first roller than each discharge position.

  The image forming apparatus may further include a measurement unit such as an encoder. Hereinafter, an example in which the measurement unit is realized by an encoder will be described. Specifically, the encoder is installed with respect to the rotation shaft of the roller 230, for example. In this way, the conveyance amount in the conveyance direction can be measured based on the rotation amount of the roller 230. When this measurement result is used together with the detection result by the sensor, the image forming apparatus can discharge the liquid onto the web 120 with higher accuracy.

  FIG. 10 is a diagram illustrating an example in which the position of the recording medium varies in the orthogonal direction. Hereinafter, an example in which the web 120 is transported in the transport direction 10 as illustrated in FIG. As shown in this example, the web 120 is conveyed by a roller or the like. Thus, when the web 120 is conveyed, the position of the web 120 may fluctuate in the orthogonal direction as shown in FIG. 10B, for example. That is, the web 120 may “meander” as shown in FIG.

  The variation in the position of the web 120 in the orthogonal direction, that is, “meandering” occurs due to, for example, eccentricity of rollers related to conveyance, misalignment, or cutting of the web 120 by a blade. In addition, when the web 120 is narrow in the orthogonal direction, the thermal expansion of the roller may affect the variation in the position of the web 120 in the orthogonal direction.

  FIG. 11 is a diagram illustrating an example of a cause of color misregistration. As described with reference to FIG. 10, when the position of the recording medium fluctuates in the orthogonal direction, that is, “meandering” occurs, color misregistration is likely to occur due to the cause shown in FIG.

  Specifically, when an image is formed on a recording medium using a plurality of colors, that is, when a color image is formed, the image forming apparatus discharges each liquid discharge head unit as illustrated. A color image by a so-called color plane is formed on the web 120 by superimposing the inks of the respective colors.

  On the other hand, there is a position variation as described in FIG. For example, “meandering” may occur based on the reference line 320. In this case, when each liquid discharge head unit discharges ink to the same position, the position of the web 120 fluctuates in the orthogonal direction due to “meandering” between the liquid discharge head units. May occur. That is, the color misalignment 330 occurs because the line formed by the ink ejected by each liquid ejection head unit is misaligned in the orthogonal direction. As described above, when the color misregistration 330 occurs, the image quality of the image formed on the web 120 may deteriorate.

<Example of control unit>
The controller 520 (FIG. 2), which is an example of the control unit, has a configuration described below, for example.

  FIG. 12 is a block diagram illustrating an example of a hardware configuration of a control unit according to an embodiment of the present invention. For example, the controller 520 includes a host device 71 that is an information processing device and the like, and a printer device 72. In the illustrated example, the controller 520 causes the printer device 72 to form an image on the recording medium based on the image data and control data input from the host device 71.

  The host device 71 is, for example, a PC (Personal Computer). The printer device 72 includes a printer controller 72C and a printer engine 72E.

  The printer controller 72C controls the operation of the printer engine 72E. First, the printer controller 72C transmits / receives control data to / from the host device 71 via the control line 70LC. Further, the printer controller 72C transmits / receives control data to / from the printer engine 72E via the control line 72LC. By transmitting and receiving this control data, various printing conditions and the like indicated by the control data are input to the printer controller 72C, and the printer controller 72C stores the printing conditions and the like using a register or the like. Next, the printer controller 72C controls the printer engine 72E based on the control data, and forms an image according to the print job data, that is, the control data.

  The printer controller 72C includes a CPU 72Cp, a print control device 72Cc, and a storage device 72Cm. The CPU 72Cp and the print control device 72Cc are connected by a bus 72Cb and communicate with each other. The bus 72Cb is connected to the control line 70LC via a communication I / F (interface) or the like.

  The CPU 72Cp controls the operation of the entire printer device 72 by a control program or the like. That is, the CPU 72Cp is an arithmetic device and a control device.

  Based on the control data transmitted from the host device 71, the print control device 72Cc transmits / receives data indicating a command or status to the printer engine 72E. Thereby, the print control device 72Cc controls the printer engine 72E. Further, the storage unit 110F3 illustrated in FIG. 8 is realized by, for example, the storage device 72Cm. Furthermore, the speed calculation unit 110F4 illustrated in FIG. 8 is realized by, for example, the CPU 72Cp. Note that the storage unit 110F3 and the speed calculation unit 110F4 may be realized by other calculation devices and storage devices.

  Data lines 70LD-C, 70LD-M, 70LD-Y and 70LD-K, that is, a plurality of data lines are connected to the printer engine 72E. Then, the printer engine 72E receives image data from the upper apparatus 71 via a plurality of data lines. Next, the printer engine 72E performs image formation for each color based on control by the printer controller 72C.

  The printer engine 72E includes data management devices 72EC, 72EM, 72EY, and 72EK, that is, a plurality of data management devices. The printer engine 72E includes an image output device 72Ei and a conveyance control device 72Ec.

  FIG. 13 is a block diagram illustrating an example of a hardware configuration of a data management apparatus included in a control unit according to an embodiment of the present invention. For example, the plurality of data management devices have the same configuration. Hereinafter, an example in which each data management device has the same configuration will be described, and the data management device 72EC will be described as an example. Therefore, the overlapping description is omitted.

  The data management device 72EC includes a logic circuit 72ECl and a storage device 72ECm. As shown in the figure, the logic circuit 72ECl is connected to the host device 71 via the data line 70LD-C. Further, the logic circuit 72ECl is connected to the print control device 72Cc via the control line 72LC. The logic circuit 72ECl is realized by an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or the like.

  The logic circuit 72ECl stores the image data input from the host device 71 in the storage device 72ECm based on the control signal input from the printer controller 72C (FIG. 12).

  The logic circuit 72ECl reads cyan image data Ic from the storage device 72ECm based on a control signal input from the printer controller 72C. Next, the logic circuit 72ECl sends the read cyan image data Ic to the image output device 72Ei.

  Note that the storage device 72ECm desirably has a capacity capable of storing image data of about three pages. When image data of about three pages can be stored, the storage device 72ECm can store image data input from the host device 71, image data during image formation, and image data for next image formation.

  FIG. 14 is a block diagram illustrating an example of a hardware configuration of an image output apparatus included in a control unit according to an embodiment of the present invention. As shown in the figure, the image output device 72Ei includes an output control device 72Eic, a black liquid discharge head unit 210K, a cyan liquid discharge head unit 210C, a magenta liquid discharge head unit 210M, and a yellow liquid discharge head that are liquid discharge head units for each color. Unit 210Y.

  The output control device 72Eic outputs the image data of each color to the liquid ejection head unit of each color. In other words, the output control device 72Eic controls the liquid discharge head unit of each color based on the input image data.

  The output control device 72Eic controls a plurality of liquid ejection head units simultaneously or individually. That is, the output control device 72Eic performs control to change the timing at which each liquid ejection head unit ejects liquid in response to timing input. Note that the output control device 72Eic may control any of the liquid discharge head units based on a control signal input from the printer controller 72C (FIG. 12). Further, the output control device 72Eic may control any of the liquid ejection head units based on an operation by the user.

  Note that the printer device 72 shown in FIG. 12 has different routes for inputting image data from the host device 71 and routes used for transmission / reception between the host device 71 and the printer device 72 based on the control data. It is an example.

  The printer device 72 may be configured to form an image with one black color, for example. In order to increase the speed of image formation when performing image formation with one black color, for example, a configuration including one data management device and four black liquid discharge head units may be used. In this way, black ink is ejected by each of the plurality of black liquid ejection head units. Therefore, it is possible to perform faster image formation as compared with a configuration in which one black liquid discharge head unit is used.

  The conveyance control device 72Ec (FIG. 12) is an actuator, a mechanism, a driver device, or the like that conveys the web 120. For example, the conveyance control device 72Ec controls a motor or the like connected to each roller or the like to convey the web 120.

<Example of overall processing>
FIG. 15 is a flowchart illustrating an example of the entire process performed by the apparatus for ejecting liquid according to an embodiment of the present invention. For example, it is assumed that image data indicating an image formed in advance on the web 120 (FIG. 1) is input to the image forming apparatus 110. Next, the image forming apparatus 110 performs the entire process shown in FIG. 15 based on the image data, and forms an image indicated by the image data on the web 120.

  In step S01, the image forming apparatus detects the conveyance speed in the conveyance direction or the orthogonal direction. That is, in step S01, the image forming apparatus detects the conveyance speed at which the web 120 is conveyed in at least one of the conveyance direction and the orthogonal direction by the sensor.

  In step S02, the image forming apparatus determines whether the conveyance speed has been changed based on the conveyance speed detected in step S01. Next, when it is determined that the conveyance speed has been changed (YES in step S02), the image forming apparatus proceeds to step S03. On the other hand, if it is determined that the conveyance speed has not been changed (NO in step S02), the image forming apparatus ends the process.

  In step S03, the image forming apparatus calculates an optical zoom magnification. For example, the optical zoom magnification is calculated based on the above equation (5) and the like.

  In step S04, the image forming apparatus sets the optical zoom magnification calculated in step S03.

  FIG. 16 is a diagram illustrating an example of the optical zoom magnification set by the apparatus for ejecting liquid according to an embodiment of the present invention. When the processing shown in FIG. 15 is performed, for example, the optical zoom magnification as illustrated is obtained.

  Hereinafter, an example in which a zoom lens ZM as illustrated is used will be described. As shown in the figure, the position of the zoom lens ZM is changed by an actuator ACA or the like based on the set optical zoom magnification.

  The image forming apparatus is set so that the optical zoom magnification decreases as the conveyance speed V increases. In this way, when the conveyance speed V increases, the shutter speed is often set to increase. As the shutter speed increases, the exposure time tends to be shorter. When the exposure time is shortened, the amount of received light is reduced, so that the image tends to be dark. Accordingly, when the optical zoom magnification is lowered, the image forming apparatus can increase the amount of received light, and therefore can capture a bright image even when the shutter speed is high. Also, if the optical zoom magnification is low, the amount of blurring for one pixel can be reduced. Therefore, the image forming apparatus can accurately detect the position of the object to be conveyed in the conveyance direction or the orthogonal direction.

  The optical zoom magnification may be a continuous set value or a discrete set value.

  Further, when there is a light source variation or CMOS sensor sensitivity variation, the image forming apparatus may adjust the amount of received light based on the variation.

  Further, when the received light amount is adjusted by the optical zoom magnification, the digital zoom magnification or the like may be further adjusted in order to adjust the size of the image.

<Example of processing results>
FIG. 17 is a diagram illustrating an example of a test pattern used by an apparatus for ejecting liquid according to an embodiment of the present invention. First, as shown in the drawing, the image forming apparatus performs test printing so that a straight line is formed in the transport direction 10 with black as an example of the first color. The distance Lk from the edge is obtained from the result of this test printing. In this manner, when the distance Lk from the edge is adjusted manually or by an apparatus in the orthogonal direction, the position at which the first color, that is, the black ink serving as the reference is ejected is determined.

  FIG. 18 is a diagram illustrating an example of a processing result of the overall processing by the apparatus for ejecting liquid according to an embodiment of the present invention. For example, as shown in FIG. 18A, it is assumed that image formation is performed in the order of black, cyan, magenta, and yellow. FIG. 18B is a plan view of FIG. 18A viewed from above, a so-called plan view. Hereinafter, an example in which the roller 230 is eccentric will be described. Specifically, it is assumed that there is an eccentric EC as shown in FIG. As described above, when there is an eccentric EC, a shaking OS is generated in the roller 230 when the web 120 is conveyed. As described above, when the shaking OS occurs, the position POS of the web 120 changes. That is, “meandering” is generated by the shaking OS.

  In order to reduce the color misregistration with respect to black, the image forming apparatus subtracts the current position of the recording medium detected by the sensor and the position of the recording medium one cycle before, thereby changing the position of the recording medium. calculate. Specifically, first, the difference between the position of the web 120 detected by the black sensor SENK and the position of the web 120 under the black liquid discharge head unit 210K is defined as “Pk”. Similarly, the difference between the position of the web 120 detected by the cyan sensor SENC and the position of the web 120 under the cyan liquid discharge head unit 210C is defined as “Pc”. Further, the difference between the position of the web 120 detected by the magenta sensor SENM and the position of the web 120 under the magenta liquid ejection head unit 210M is defined as “Pm”. Furthermore, the difference between the position of the web 120 detected by the yellow sensor SENY and the position of the web 120 under the yellow liquid discharge head unit 210Y is defined as “Py”.

  Subsequently, the position where the liquid is landed by each liquid discharge head unit and the distance from the edge of the web 120, that is, the edge of the web 120, for each color, “Lk3”, “Lc3”, “Lm3”, and “Ly3”. " In such a case, since the position of the web 120 is detected by the sensor, “Pk = 0”, “Pc = 0”, “Pm = 0”, and “Py = 0”. From this relationship, the following relationship (6) can be expressed.

Lc3 = Lk3-Pc = Lk3
Lm3 = Lk3
Ly3 = Lk3-Py = Lk3 (6)
Therefore, from the above equation (6), “Lk3 = Lm3 = Lc3 = Ly3”. In this manner, the image forming apparatus can further improve the accuracy of the landing position of the discharged liquid in the orthogonal direction by moving each liquid discharge head unit to change the position of the web 120. Further, when image formation is performed, each color liquid is landed with high accuracy, so that color misregistration can be reduced and the image quality of the formed image can be improved.

  Further, it is desirable that the sensor is installed at a position closer to the first roller than the discharge position.

  FIG. 19 is a diagram illustrating an example of a position where a sensor is installed in a device for ejecting liquid according to an embodiment of the present invention. Hereinafter, black will be described as an example. In this example, the black sensor SENK is preferably installed between the first black roller CR1K and the second black roller CR2K and closer to the first black roller CR1K than the black discharge position PK. . The distance approaching the first black roller CR1K is determined based on the time required for the control operation. For example, the distance approaching the first black roller CR1K is “20 mm”. In this case, the position where the black sensor SENK is installed is an example of “20 mm” upstream from the black discharge position PK.

  Thus, when the position where the sensor is installed is close to the ejection position, the detection error E1 becomes small. Further, when the detection error E1 is small, the image forming apparatus can land each color liquid with high accuracy. For this reason, when image formation is performed, the image forming apparatus landes each color liquid with high accuracy, so that color misregistration can be reduced and the image quality of the formed image can be improved.

  Further, with such a configuration, for example, there is no restriction that the distance between the liquid discharge head units must be an integral multiple of the circular length d (FIG. 18) of the roller, so the liquid discharge head unit is installed. The position can be freely set. That is, the image forming apparatus can land each color liquid with high accuracy even when the distance between the liquid discharge head units is a non-integer multiple of the circular length d of the roller.

<Comparative example>
FIG. 20 is a diagram illustrating an example of a hardware configuration in the first comparative example. The first comparative example shown in the figure detects the position of the web 120 before reaching the position where each liquid discharge head unit discharges the liquid. For example, in this comparative example, the position where the sensor is installed is a position that is “200 mm” from directly under the liquid discharge head unit. Based on the detection result in this case, the image forming apparatus according to the first comparative example moves the liquid ejection head unit to compensate for the positional variation of the recording medium.

  FIG. 21 is a diagram illustrating a processing result example of the overall processing by the apparatus for ejecting liquid according to the first comparative example. In this comparative example, the liquid discharge head units are installed so that the distance between the liquid discharge head units is an integral multiple of the circular length d of the roller. In this case, the difference between the web position detected by each sensor and the web position immediately below the liquid discharge head unit is “0”. Therefore, in this comparative example, assuming that the landing positions of the liquid on the ink webs of the respective colors are the distances “Lk1”, “Lc1”, “Lm1”, and “Ly1” from the web edge, “Lk1 = Lc1 = Lm1 = Ly1”. " In this way, the positional deviation is corrected.

  FIG. 22 is a diagram illustrating a processing result example of the entire processing by the apparatus for ejecting liquid according to the second comparative example. Note that the second comparative example has the same hardware configuration as the first comparative example. Compared to the first comparative example, the second comparative example is different in that the distance between the black and cyan liquid ejection head units and the distance between the magenta and yellow liquid ejection head units are “1.75d”, respectively. That is, the second comparative example is an example in which the distance between the black and cyan liquid discharge head units and the distance between the magenta and yellow liquid discharge head units are each a non-integer multiple of the circle length d of the roller.

  In this second comparative example, the difference between the web position detected by the black sensor SENK and the web position under the black liquid discharge head unit 210K is defined as “Pk”. Similarly, the difference between the web position detected by the cyan sensor SENC and the web position under the cyan liquid discharge head unit 210C is defined as “Pc”. Further, the difference between the position of the web detected by the magenta sensor SENM and the position of the web 120 under the magenta liquid ejection head unit 210M is defined as “Pm”. Furthermore, the difference between the position of the web detected by the yellow sensor SENY and the position of the web 120 under the yellow liquid discharge head unit 210Y is defined as “Py”. Further, in the second comparative example, assuming that the liquid landing position on the web of each color ink is the distances “Lk2,” “Lc2,” “Lm2,” and “Ly2” from the web edge, Can show the relationship.

Lc2 = Lk2-Pc
Lm2 = Lk2
Ly2 = Lk2-Py (7)
Therefore, “Lk2 = Lm2 ≠ Lc2 = Ly2”. Thus, when the distance between the liquid discharge head units is a non-integer multiple of the circular length d of the roller, in this comparative example, the position of the web immediately below the cyan liquid discharge head unit 210C and the magenta liquid discharge head unit 210M. Is different by “Pc” and “Py”. For this reason, web position fluctuations are not compensated, and color misregistration or the like is likely to occur.

  FIG. 23 is a diagram illustrating an example of a position where a sensor is installed in the apparatus for ejecting liquid according to the comparative example. As shown in the figure, the comparative example is a case where the sensor is installed at a position far from the discharge position. Therefore, the detection error E2 in the comparative example often becomes large.

<Functional configuration example>
FIG. 24 is a functional block diagram showing an example of a functional configuration of a device for ejecting liquid according to an embodiment of the present invention. As illustrated, the image forming apparatus 110 includes a plurality of liquid ejection head units and a detection unit 110F10 for each liquid ejection head unit. Further, the image forming apparatus 110 includes a control unit 54F and a setting unit 55F.

  As shown in the drawing, the detection unit 110F10 is provided for each liquid ejection head unit. Specifically, in the example illustrated in FIG. 2, the number of detection units 110F10 is four as illustrated. The detection unit 110F10 detects the position of the recording medium in the conveyance direction or the orthogonal direction of the web 120. The detection unit 110F10 is realized by, for example, the hardware configuration illustrated in FIG. 4 or FIG. And detection part 110F10 outputs the detection result which shows the conveyance speed of the to-be-conveyed object in at least one of the conveyance direction in which a to-be-conveyed object is conveyed, or a orthogonal direction with respect to a conveyance direction using an optical sensor. The detection unit 110F10 is the detection units 52A and 52B and the like in FIG.

  As shown in the figure, the first roller is provided for each liquid ejection head unit. Specifically, in the example illustrated in FIG. 2, the number of first rollers is four, which is the same number as the liquid discharge head unit. The first roller is a roller used to transport the recording medium to a discharge position where the liquid discharge head unit can discharge the liquid to a predetermined portion of the recording medium. That is, a 1st roller is a roller installed in an upstream from each discharge position. For example, in the case of black, the first roller is the first black roller CR1K (FIG. 2).

  As shown in the figure, the second roller is provided for each liquid ejection head unit. Specifically, in the example illustrated in FIG. 2, the number of second rollers is four, which is the same number as the liquid discharge head unit. The second roller is a roller used to convey the recording medium from the discharge position to another position. That is, a 2nd roller is a roller installed downstream from each discharge position. For example, in the case of black, the second roller is a black second roller CR2K (FIG. 2).

  The setting unit 55F sets the optical zoom magnification according to the optical sensor used by the detection unit 110F10 based on the transport speed.

  Note that the image forming apparatus 110 may further include a moving unit that moves each of the liquid discharge head units based on the detection result.

  Desirably, the position where the detection unit 110F10 performs detection, that is, the position where the sensor is installed, is close to the discharge position such as the black discharge position PK, such as the inter-black roller INTK1. That is, when detection is performed using the inter-black roller INTK1 or the like, the image forming apparatus 110 can accurately detect the position of the recording medium in the conveyance direction or the orthogonal direction.

  More preferably, the position where the detection unit 110F10 performs detection, that is, the position where the sensor is installed is the position upstream of the discharge position among the rollers as in the black upstream section INTK2. Better. That is, when the detection is performed in the black upstream section INTK2 or the like, the image forming apparatus 110 can accurately detect the position of the recording medium in the transport direction or the orthogonal direction.

<Summary>
An apparatus for ejecting liquid according to an embodiment of the present invention includes a transported object detection device having an optical sensor or the like. And the to-be-conveyed object detection apparatus 60 is provided with the detection part 110F10 and the setting part 55F, and sets an optical zoom magnification based on a conveyance speed. As a result, the transported object detection device 60 can accurately detect the position of the transported object in the transport direction or the orthogonal direction.

  An apparatus for discharging a liquid according to an embodiment of the present invention detects the position of a transported object such as a recording medium in a transport direction or an orthogonal direction at a position close to the liquid discharge head unit for each liquid discharge head unit. Next, the apparatus for ejecting liquid according to an embodiment of the present invention moves the liquid ejection head unit based on the detection result. Therefore, an apparatus for ejecting a liquid according to an embodiment of the present invention ejects a liquid according to an embodiment of the present invention as compared with the first comparative example and the second comparative example shown in FIGS. The apparatus that compensates for the deviation generated at the landing position of the liquid in the orthogonal direction with high accuracy.

  Further, in the apparatus for ejecting liquid according to one embodiment of the present invention, each liquid ejection head unit need not be arranged at a position obtained by multiplying the circumferential length of the roller by an integer, as in the first comparative example. It is possible to reduce restrictions on installing the discharge head unit. In the first comparative example and the second comparative example, adjustment is not possible without an actuator in the first color, that is, in this example, black. In contrast, the apparatus for ejecting liquid according to an embodiment of the present invention can further improve the accuracy of the landing position of the ejected liquid in the orthogonal direction even for the first color.

  In addition, when an image is formed on a recording medium by ejecting liquid, the device for ejecting liquid according to an embodiment of the present invention causes color misregistration when the landing positions of the ejected liquids of each color become accurate. As a result, the image quality of the formed image can be improved.

  The apparatus for ejecting liquid according to the present invention may be realized by a system for ejecting liquid having one or more apparatuses. For example, the black liquid discharge head unit 210K and the cyan liquid discharge head unit 210C are apparatuses in the same casing, and the magenta liquid discharge head unit 210M and the yellow liquid discharge head unit 210Y are apparatuses in the same casing, both of which are included. You may implement | achieve by the system which discharges a liquid.

  Further, in the apparatus for ejecting liquid and the system for ejecting liquid according to the present invention, the liquid is not limited to ink, and may be another type of recording liquid or fixing processing liquid. In other words, the apparatus for ejecting liquid and the system for ejecting liquid according to the present invention may be applied to an apparatus for ejecting a liquid of a type other than ink.

  Therefore, the apparatus for ejecting liquid and the system for ejecting liquid according to the present invention are not limited to forming an image. For example, the formed object may be a three-dimensional structure.

  Further, the conveyed object is not limited to a recording medium such as paper. The material to be conveyed may be a material to which a liquid can adhere. For example, the material to which the liquid can be attached is not limited as long as the liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or a combination thereof can be attached temporarily.

  In the embodiment according to the present invention, the image forming apparatus, the information processing apparatus, or a combination thereof may be implemented by a program for causing a computer to execute a part or all of the transported object detection method.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Or it can be changed.

60 Conveyed object detection device 110 Image forming device 120 Web 210K Black liquid ejection head unit 210C Cyan liquid ejection head unit 210M Magenta liquid ejection head unit 210Y Yellow liquid ejection head unit SENK Black sensor SENC Cyan sensor SENM Magenta sensor SENY Yellow Sensor 520 controller

Japanese Patent Laying-Open No. 2015-13476

Claims (16)

An optical sensor for receiving the light reflected by the conveyed object;
A setting unit for setting an optical zoom magnification according to the optical sensor based on a speed at which the object is conveyed;
A detection unit that outputs a detection result indicating a position or speed of the object to be conveyed in at least one of a conveyance direction in which the object to be conveyed is conveyed or a direction orthogonal to the conveyance direction using the optical sensor;
A to-be-conveyed object detection apparatus. The transport object detection device according to claim 1, wherein the setting unit receives a speed at which the transport object is transported from outside. The transported object detection device according to claim 1, wherein the setting unit sets the optical zoom magnification based on the speed output from the detection unit.   The said detection part calculates | requires the said detection result based on the pattern which the said to-be-conveyed object has, The to-be-conveyed object detection apparatus of any one of Claim 1 thru | or 3 characterized by the above-mentioned. The pattern is generated by interference of light applied to the uneven shape formed on the transported object,
The said detection part calculates | requires the said detection result based on the image which imaged the said pattern, The to-be-conveyed object detection apparatus of Claim 4 characterized by the above-mentioned. The said detection part detects the position of the said to-be-conveyed object based on the result of having detected the said pattern at two or more different timings. The to-be-conveyed object detection apparatus of Claim 4 or 5 characterized by the above-mentioned. The transported object detection apparatus according to claim 1, wherein the setting unit sets a shutter speed of the optical sensor based on the speed. A transported object detection device according to claim 1, comprising a plurality of liquid discharge head units, wherein each liquid discharge head unit is on the transport path with respect to the transported object. A device for discharging liquid at different positions of
An apparatus for ejecting liquid, comprising: a control unit that causes the liquid ejection head unit to eject liquid based on the detection result of the transported object detection apparatus. The detection unit is provided in each of the liquid discharge head units, and is provided upstream of a position where the liquid discharged by the liquid discharge head unit lands on the transferred object, and is used for transferring the transferred object. A first roller,
A second roller provided in each of the liquid discharge head units, provided on a downstream side of a position where the liquid discharged by the liquid discharge head unit lands on the transferred object, and used for transferring the transferred object; ,
The apparatus for ejecting liquid according to claim 8, installed between the first roller and the second roller of each of the liquid ejection head units.   The apparatus for discharging liquid according to claim 9, wherein the position of the detection unit is a position between the landing position and the first roller. The apparatus for discharging a liquid according to any one of claims 8 to 10, further comprising a moving unit that moves the liquid discharge head unit in a direction orthogonal to a direction in which the object to be transferred is transferred. .   The apparatus for ejecting liquid according to claim 8, wherein the liquid is ejected based on the detection result in a transport direction in which the object is transported.   The apparatus for discharging a liquid according to claim 8, wherein the object to be transported is long.   The apparatus for ejecting liquid according to claim 8, wherein when the liquid is ejected, an image is formed on the object to be transported. A transported object detection method performed by a transported object detection device having an optical sensor that receives light reflected by a transported object,
A setting procedure for setting the optical zoom magnification of the optical sensor based on a speed at which the transported object is transported by the transported object detection device;
Detection result indicating the position or speed of the object to be conveyed in at least one of the conveyance direction in which the object to be conveyed is conveyed or the direction orthogonal to the conveyance direction using the optical sensor. Detection procedure to output
A method for detecting an object to be conveyed. A program for causing a computer having an optical sensor that receives light reflected by a conveyed object to execute the conveyed object detection method,
A setting procedure in which the computer sets an optical zoom magnification according to the optical sensor based on a speed at which the object is conveyed;
Detection in which the computer uses the optical sensor to output a detection result indicating a position or speed of the transported object in at least one of a transport direction in which the transported object is transported or a direction orthogonal to the transport direction. Procedure and
A program for running

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